The present invention relates generally to thermal barriers for use in a temperature controlled cabinet and more particularly to a thermal barrier curtain that allows the air from within the cabinet to circulate to the storage area of the cabinet door.
Commercial businesses as well as private homes commonly use refrigerators to preserve the freshness of food by regulating the temperature to a level sufficient to slow food aging and to reduce contamination by bacteria. Consumption of food contaminated with bacteria often results in what is generally called food poisoning and is a common problem with improperly stored foods.
Shell eggs are among the most nutritious foods and are recommended as part of a healthy diet, but they are extremely susceptible to the bacteria Salmonella Enteriditis. Salmonella Enteriditis attaches to the shell surface during the egg laying process or when the egg comes in contact with feces prior to collection. Much of the bacteria is removed during the washing and sanitizing process prior to sale, however as with most processes, they may not eradicate all of the bacteria. In addition if an egg rests against already contaminated food or is handled with contaminated hands, the bacteria may be reintroduced on the eggshell. Bacterial growth is facilitated when condensation accumulates on the exterior of the eggshell surface often times resulting when the refrigerator door is opened. Because of this several government agencies recommend not leaving eggs at ambient temperature for more than two hours after refrigeration.
The safety of shell eggs has been a long term problem and has prompted the Federal Drug Administration (FDA), Animal Plant Health Inspection Service (AIPHIS), Food Safety and Inspection Service (FSIS), Agricultural Research Service (ARS), National Agricultural Statistics Service (NASS), as well as state agriculture departments and state and local health departments to cooperate to ensure the safety of shell eggs from farm to table. On Aug. 27, 1999 the FSIS ruled that shell eggs packed for consumers must be stored and transported under refrigeration at an ambient temperature not to exceed 45xc2x0 F. However, the recommendation for home storage of eggs by the FSIS is even stricter. The FSIS recommends consumers transport eggs immediately to a refrigerator and store them immediately at or below 40xc2x0 F. to decrease the likelihood of Salmonella Enteriditis contamination.
The FSIS suggests keeping eggs within the coldest region of the refrigerator and not in the storage door. However, even with this warning many consumers still keep their eggs in the door of the refrigerator. Moreover, many manufacturers have incorporated removable egg trays that fit in the storage door and still others have molded egg trays built into the storage door. These conveniences offered by manufacturers further encourage consumers to store eggs in the door of the refrigerator.
Nearly every home in the U.S. has a refrigerator, and the power they require add to the already high demand for electricity. There is a constant tension between the FSIS recommendations, which encourage adequate refrigeration to ensure food safety and the Department of Energy (DOE) concerns that stress energy conservation.
The Association of Home Appliance Manufacturers (xe2x80x9cAHAMxe2x80x9d) has adopted a standard voluntary testing protocol (ANSI/AHAM HRF-1-1988) recognized by the American National Standards Institute (xe2x80x9cANSIxe2x80x9d) for testing the efficiency of home refrigerators. The protocol measures the temperature at strategic points in the interior refrigerator and freezer chambers over time while opening and closing the door at defined intervals. AHAM standards allow consumers to identify which refrigerators use less power and which better maintain the set temperature under conditions of normal consumer use (i.e. when refrigerator doors are frequently opened and closed during the day).
Various forms of thermal barriers have been developed in an attempt to reduce the power consumption by refrigerators. Thermal barriers reduce the interaction between the cold interior air of the refrigerator and the warmer outside ambient air. The result is a refrigerator that uses less power to retain the set temperature by reducing loss of the cold air when the door is open. Examples of such known devices are disclosed in U.S. Pat. Nos. 2,041,258, 4,109,484, 4,288,992, 4,313,485, 4,400,046, 4,429,548, 4,539,819, 5,431,490. Generally, these devices create a barrier between the inner cabinet and the outer environment by providing rigid drawers or doors, a draped over horizontal curtain, or a hanging vertical curtain. However, these devices are intended and designed to isolate a refrigerated chamber without a storage door. Unfortunately, a storage door is a common feature in many brands of household and industrial refrigerators.
U.S. Pat. No. 5,431,490 (xe2x80x9c""490xe2x80x9d) has incorporated the use of a hanging vertical thermal barrier with vertical slits in a refrigerator having a storage door. Unfortunately the ""490 invention does not continually retain a storage door temperature at or below the FSIS requirement of 45xc2x0 F. when performing the AHAM test.
As previously discussed, current devices allow the efficient storage of food by creating thermal barriers in refrigerators that do not have storage doors. However, these thermal barriers are unable to maintain temperatures in food storage doors that meet the FSIS recommendations. Therefore, there is a need for a thermal barrier that allows efficient cooling of the storage door while minimizing the loss of coolness from the freshness chamber when the door is open.